Claim or Concession
Law 69 B2 states:
Agreement with a claim or concession may be withdrawn within the Correction Period established under Law 79C:
2. If a player has agreed to the loss of a trick his side would likely have won had the play continued.
Law 71B states:
A concession must stand, once made, except that within the Correction Period established under Law 79C the Director shall cancel a concession:
B: If a player has conceded a trick that could not be lost by any normal play of the remaining cards.
I would imagine that the Director would only cancel a concession under Law 71B if the player concerned asks for it. How is this different from withdrawing a concession under Law 69?
Secondly, presumably there is a subtle difference between 'loss of a trick his side would likely have won had the play continued' and 'a trick that could not be lost by any normal play of the cards'. This difference escapes me - if you cannot lose a trick then you must win it!
Grateful if anybody can clarify this for me.